[Richard]

Good Morning.

Bear with me, for I am a Southern boy born and raised, and we never take the short way to tell anything.

For years after I installed the Lithium pack that I obtained from Forest, I poured over the literature from the manufacturers, and other well versed Lithium installers. I was obsessed with setting the charger to get full use of the batteries without frying my investment. What I discovered was a myriad of opinions on how to do it, and a whole lot of chest pounding over 100ths of a volt. I found a ton of conflicting information and opinions. Then I stumbled into a thread, and a person who seemed to have his head on level made a statement that completely changed my understanding of how to set the batteries up. He said “the batteries will tell you”. What he meant was that if you will take the time to carefully monitor your battery bank through an extended charge and discharge cycle where you intentionally charge into the sharp up curve in voltage and intentionally discharge into the sharp down curve in voltage, then the batteries will tell you where those inflection points are instead of reading tons of conflicting info about where someone thinks they are in theory. The beauty of doing that is that you take out differences in meters, differences in monitoring systems, and differences in wiring. You read the voltages on YOUR system, the one that will be used to maintain and use the bank.

In the short term, I don’t think you need to go that far, but regardless of what you do with charge profiles, you need a critical piece of info from YOUR setup. Turn off the charger and let the batteries go for 8 hrs with normal loads on them. What is the starting voltage when you turned off the charger, and what is the voltage after 8 hours? Since the useful part of lithium setups is flat, the voltage after 8 hours should be very close to YOUR voltage at the flat part of the curve. IF you have the recharge voltage set above that number, then you will continually operate above where the batteries are happiest.

You were correct, with CC/CV, Magnum does not allow a float voltage. They do allow you to hold the batteries at the CV level, but you do not want to hold them that high. So you have a choice to make. You can use the CC/CV setting, but you will always yo yo the batteries since that setup dictates a full charge and recharge when hitting the recharge voltage. OR, you can revert to a custom setup, which allows float, and this eliminates the yo yo. These are your options unless you change to a different charger.

If sticking with the CC/CV setup, I would make two changes to your existing setup parameters. One, I would lower the recharge voltage to 0.3 volts less than the resting voltage determined in the 8 hour test. Two, change the CV Charge Done to amps instead of time. Use 30 amps as the value, since you have a 600 AHr bank, and a good starting point is 5% of the bank size. You can tweak later if you want a higher of lower ending SOC. Again, the End Charge on Amps is based on “the batteries will tell you”. When the batteries stop accepting the higher currents they are nearing full so if you end the charge when the current drops the charger is responding to hints from the batteries that they are full. If you leave the charge done on time, the charger is simply going to hold the voltage for that given time regardless of what the batteries need. That’s not a terrible thing because the amperage will drop, but you run the risk of holding the lithiums at a higher voltage then necessary to get the charge level you desire. On a side note, I ran the CC/CV profile for about a year, but I had the values set conservatively, and I noticed I didn’t seem to have much capacity. That was before I learned about “the batteries will tell you”.

If you want to float the batteries to avoid the constant yo yo of cycling them, then we can set up a Custom profile that will do EXACTLY what the CC/CV does except the charger will go into float when the charge cycle is finished, instead of going into quiet mode. It is obvious that I prefer this option. It has one drawback, that you must be aware of. Depending on where you set the float voltage, it will not hold the battery pack at 90% SOC, probably somewhere between 30 and 70 SOC. If plugged in, I don’t care. However, if I know that I will be off grid for a while, I go to Control and manually start the Charge cycle. No big deal.

I have the Magnum, with the addition of the BMK (battery monitor kit), it allows me to use the Magnum remote to monitor SOC, and it provides more accurate amperage measurements.

Forest handles his a little differently, but he has different equipment with different capabilities than you do. His way works very well also.

Sorry for the treatise. Hopefully it helps when you talk with Battleborn.